3.2.2. Morphological analysis of foramen magnum in African small Pangolin (P. tricuspis) in stepwise reconstruction
Stepwise foramen magnum outline reconstruction in P. tricspisrevealed better accuracy with increasing harmonic numbers from the 1st to 14th as presented visually in Fig. 5. The accuracy of this as shown by the fit index of original vs reconstructed values is about 97% (Fig. 6). Fifty-two (52) principal components coefficients were analyzed with 14 harmonics with a total variance of 1.276294E-001, the first 4 principal components yielded effective description of the foramen outlines (Table 6).
Figure 5 Contour reconstructions of the foramen magnum outlines in Small African Pangolins (P. tricuspis ) for the first 14 harmonics (Overlapped reconstructions -2std= +std Red, mean is green, -std yellow)
Figure 6 Allometric analysis of the foramen magnum outline (P.tricuspis ) in caudal view showing fit diagram of incremental EF harmonics evaluated from discriminant analysis
A full morphologic description of the outlines was achieved in evaluated samples by the 5th harmonic followed by finer details from the 6th to 14th harmonic. The first portion to be morphologically characterized from a graphic central point was the direct dorsal and ventral rims in a clockwise direction by the 1st harmonic, the left dorsolateral aspect in caudal perspective in relation to the central point was perfectly elucidated by PC2 whereas PC3 explained the right dorso-lateral and left ventro-lateral aspects at the condylar rims, the 4thharmonic was more diffuse and at variance focusing on the right and left lateral rims (Figs. 2b and 5). The last parts to be reconstructed were the left dorso-lateral left lateral and left ventro-lateral rims in a dorso-ventral direction (5th - 14thharmonics). Components of its asymmetry were observed by the 5th harmonic accurately. Variance-covariance matrix along ontogenetic lines was between 0.0017 and 0.56, discriminant analysis in ontogeny of the sample population in stepwise harmonic increments and Mahalanobis distance (Fig. 6) demonstrated gradient decline in distance with elliptical Fourier harmonics.
Sample proportion demonstrating significant size and shape differences before was (82.3%) and (8.2%) after size normalization thus yielding 74.1% accuracy decline with size factor elimination employing size normalization (Table 7) protocol revealed shape an overriding factor. This finding satisfies the third (3rd) hypothesis of association stated for this investigation